Replacing a Signal from a Failed Sensor in a Computer System with an Estimated Signal Derived from Correlations with Other Signals

1. A method for enhancing reliability, availability and serviceability in a computer system by replacing a signal from a failed sensor with an estimated signal derived from correlations with other instrumentation signals in the computer system, comprising: determining whether a sensor has failed in the computer system, wherein an output signal from the sensor is applied to an input; and applying an estimated signal to the input in response to determining that the sensor has failed, whereby the computer system can continue operating without the failed sensor; wherein the estimated signal is derived from correlations with other instrumentation signals, wherein the instrumentation signals include at least one of: signals associated with internal performance parameters maintained by software within the computer system; signals associated with physical performance parameters measured through sensors within the computer system; and signals associated with canary performance parameters for synthetic user transactions, which are periodically generated for the purpose of measuring quality of service from an end user's perspective.

2. The method of claim 1 , wherein determining whether the sensor has failed involves: comparing the output signal from the sensor with the estimated signal to determine whether the sensor has failed.

3. The method of claim 2 , wherein comparing the output signal from the sensor with the estimated signal involves using sequential detection methods to detect changes in the relationship between the output signal from the sensor and the estimated signal.

4. The method of claim 3 , wherein the sequential detection methods include the Sequential Probability Ratio Test (SPRT).

5. The method of claim 1 , wherein prior to determining whether the sensor has failed, the method further comprises determining correlations between instrumentation signals in the computer system, whereby the correlations can subsequently be used to generate estimated signals.

6. The method of claim 5 , wherein determining the correlations involves using a non-linear, non-parametric regression technique to determine the correlations.

7. The method of claim 6 , wherein the non-linear, non-parametric regression technique can include a multivariate state estimation technique.

8. The method of claim 5 , wherein determining the correlations can involve using a neural network to determine the correlations.

9. The method of claim 1 , wherein the failed sensor can be a sensor that has totally failed, or a sensor with degraded performance.

10. A computer-readable storage medium storing instructions that when executed by a computer cause the computer to perform a method for enhancing reliability, availability and serviceability in a computer system by replacing a signal from a failed sensor with an estimated signal derived from correlations with other instrumentation signals in the computer system, the method comprising: determining whether a sensor has failed in the computer system, wherein an output signal from the sensor is applied to an input; and applying an estimated signal to the input in response to determining that the sensor has failed, whereby the computer system can continue operating without the failed sensor; wherein the estimated signal is derived from correlations with other instrumentation signals, wherein the instrumentation signals include at least one of: signals associated with internal performance parameters maintained by software within the computer system; signals associated with physical performance parameters measured through sensors within the computer system; and signals associated with canary performance parameters for synthetic user transactions, which are periodically generated for the purpose of measuring quality of service from an end user's perspective.

11. The computer-readable storage medium of claim 10 , wherein determining whether the sensor has failed involves: comparing the output signal from the sensor with the estimated signal to determine whether the sensor has failed.

12. The computer-readable storage medium of claim 11 , wherein comparing the output signal from the sensor with the estimated signal involves using sequential detection methods to detect changes in the relationship between the output signal from the sensor and the estimated signal.

13. The computer-readable storage medium of claim 12 , wherein the sequential detection methods include the Sequential Probability Ratio Test (SPRT).

14. The computer-readable storage medium of claim 10 , wherein prior to determining whether the sensor has failed, the method further comprises determining correlations between instrumentation signals in the computer system, whereby the correlations can subsequently be used to generate estimated signals.

15. The computer-readable storage medium of claim 14 , wherein determining the correlations involves using a non-linear, non-parametric regression technique to determine the correlations.

16. The computer-readable storage medium of claim 15 , wherein the non-linear, non-parametric regression technique can include a multivariate state estimation technique.

17. The computer-readable storage medium of claim 14 , wherein determining the correlations can involve using a neural network to determine the correlations.

18. The computer-readable storage medium of claim 10 , wherein the failed sensor can be a sensor that has totally failed, or a sensor with degraded performance.

19. An apparatus that enhances reliability, availability and serviceability in a computer system by replacing a signal from a failed sensor with an estimated signal derived from other instrumentation signals correlations with in the computer system, comprising: a failure determination mechanism configured to determine whether a sensor has failed in the computer system, wherein an output signal from the sensor is applied to an input; and a sensor replacement mechanism, wherein if the sensor has failed, the sensor replacement mechanism is configured to apply an estimated signal to the input, whereby the computer system can continue operating without the failed sensor; wherein the estimated signal is derived from correlations with other instrumentation signals, wherein the instrumentation signals include at least one of: signals associated with internal performance parameters maintained by software within the computer system; signals associated with physical performance parameters measured through sensors within the computer system; and signals associated with canary performance parameters for synthetic user transactions, which are periodically generated for the purpose of measuring quality of service from an end user's perspective.

20. The apparatus of claim 19 , wherein the failure determination mechanism is configured to: compare the output signal from the sensor with the estimated signal to determine whether the sensor has failed.

21. The apparatus of claim 20 , wherein the failure detection mechanism is configured to use sequential detection methods to detect changes in the relationship between the output signal from the sensor and the estimated signal.

22. The apparatus of claim 21 , wherein the sequential detection methods include the Sequential Probability Ratio Test (SPRT).

23. The apparatus of claim 19 , further comprising a correlation determination mechanism, which is configured to determine correlations between instrumentation signals in the computer system, whereby the correlations can subsequently be used to generate estimated signals.

24. The apparatus of claim 23 , wherein the correlation determination mechanism is configured to use a non-linear, non-parametric regression technique to determine the correlations.

25. The apparatus of claim 24 , wherein the non-linear, non-parametric regression technique can include a multivariate state estimation technique.

26. The apparatus of claim 23 , wherein the correlation determination mechanism is configured to use a neural network to determine the correlations.

27. The apparatus of claim 19 , wherein the failed sensor can be a sensor that has totally failed, or a sensor with degraded performance.